Telephone switch-board



E B HAMLIN 3 Sheets-Sheet 1.

TELEPHONE SWITCH BOARD.

PatentedJune 19,1883..

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TELEPHONE SWITCH BOARD.

Patented June 19,1883;

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E.-B. HAMLIN. TELEPHONE SWITGH BOARD.

No. 279-7217. Patented June 19,1883.

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UNITED STATES A TIQFFIQEQ- EVERLYN B. HAMLIN, OF CHICAGO, ILLINOIS,ASSIGNOR TO POST & OO., OF CINCINNATI, OHIO.

ITELEPHONE SWITCH-BOARD.

SPECIFICATION forming part of Letters Patent N0.'279,'74='7, dated June19, 188.

Applica ion lilnd October 7, I879.

T 00 whom it may concern:

Be it known that I, EVERLYN B. HAMLIN, of Chicago, in the county of Cookand State of Illinois, have made certain new and useful Improvements inTelephone Switch-Boards; and I do hereby declare the following to be afull, clear, and exact description of the same, sufficient to enable oneskilled in the art to which my invention belongs to make and use thesame,

I 0 reference being had to the accompanying drawings, forming a part ofthis specification, in

whichi I Figure 1, Sheet I, is a perspective view of the switch-board.Fig. 2, Sheet I, is aperspective view of one of the pins and its,connecting-socket. 3, Sheet II, is a rear elevation of the board. Fig.4, Sheet II, is a perspective view of the springswitches. Fig. 5, SheetIII, is a plan view of a modification in the arrangement of theswitches; and Fig. 6,

. Sheet III, is a diagram showing a method of connecting thetelephone-lines of several boards at a central office.

Similar letters of reference in the several fig- 2 5 ures of thedrawings indicate the same parts.

My invention has for its object to provide an improved system of makingtelephonic connections at the exchanges or central offices oftelephone-lines, and to simplify and improve the construction of theswitch-boards and their connections.

The usual method of arranging separate telephone-lines at the centraloffice consists in attaching the ends of the line-wires to separate 3 5metallic sockets placed on or in aswitch-board; To connect any two ofthese lines for the-purpose of establishing communication between anytwo subscribers, two pins or plugs joinedto gether by a wire cord areinserted in the metal 0 sockets forming the terminalsof such lines. Itfrequently happens, however, that in the course of business so manyconnections are made on a board that the crossing and interlacing of thecords confuses the operator and causes him to err in making theconnections called for. I

The first part of my invention is designed to remedy this defect; and tothat end it eonsistsi'n joining each line-wire with a metallic strip orwire connection on the board so arranged with respect to separatemetallic pinstrips that a connection shall be made between them byinserting a metal pin through the pin strip, and one of said line-stripsbeing joined to another for connecting two lines by inserting a pin inthe pin-strip of both lines. The line-strips are permanently attached tothe board and take the place of the cords connecting the pins. Thelatter are therefore free to be separately shifted, and the face of 6cthe board is prevented from being obstructed to confuse the operator.

Another feature of my invention consists in combining adisconnecting-drop with a telephone-line, so as to be thrown downat theeX- 6 5 change by a person who has been using a line, to announce thefact at theexchange that he has ceased talkingand that the line is clearfor otherconnections;

The invention also consists in the means for throwing the telephone atthe exchange into the circuit of two subscribers lines for the purposeof ascertaining if they are properly connected.

The invention further consists in connecting two or more telephoneswitch-boards at the central office by joining their correspondingpin-strips to each other, so as to continue each set throughout all theboards of the group, and in detaching the disconnecting-drops andtelephones from all the boards but one, whereby when all the boardsarenot required for con stant use two or more may be thrown together, so asto make one board, in effect, to be ma11- aged by one operator. 8 5

The invention also consists in connecting the lines of one board withthose of another board, while the independent operation of each ispreserved, to connect any two of its lines.

In the accompanying drawings, A represents a wooden switch-boardof theordinary or any preferred size and form, provided upon its face withparallel metal strips 1) I), arranged in sets of two, as shown at B, asufficient number of such setsbeing employed to accommodate the businessof the board. They are perforated at regular intervals to receive a plugor pin,

O, and hence I designate them as F pin-strips.

Similar perforated strips, D, are also arranged on the board above thesets B; but instead of being local astothat board, they are employed tocombine the lines of one board with those of other boards at the centraloffice, as I will presently describe in detail, and hence I term themcombination pin-strips. Each board is also provided with a singleperforated strip, E. placed below all the others, and it is used inmaking the connections with the call and telephone, and therefore termedthe call and telephone strip. But one of these strips is needed for eachboard.

F F are the annunciatondrops, located at any convenient point on or offthe board, and having their wires running to a common ground.

H H are parallel metal strips or wires arranged on the back of theboard, at right angles to the strips B D E on its face, but having noconnection therewith or with each other, excepting; as it is made by thepins, as I will presently describe. The strips H, which, for convenienceofdes'cri1.ition,I call Line-strips, each connects at one end with aline-wire, I, as shown in Fig. 3, forming, in effect, a continuationthereof, and therefore the line-strips on each board are equal in numberto the number of lines. Each line-strip has a connection with anannunciator-strip, J, on the face of the board when. a pin, (7, isinserted in an a1inunciator-strip, and each annunciator-strip connectedwith an annuneiator-drop by a wire, K, on the back of the board.

The pin connections between the strips of the board are made by themetatpointed pins 0 and the metal tubes or. sockets G, let into theboard.

The tubes are seated in recesses of the board, so that theirscrew-shanks 9 shall project through 'it and through the line-strips toform a metallic connection therewith. By applying nuts to the ends oftheshanks the tubes are locked in the board and the line-strips fastenedin place.

The open ends of the tubes terminate in the board a short distance fromthe strips on its face, so as to insulate them from the linc-strips.\Vhen the pins are inserted in the pin-strips their points enter thetubes, and thus form metallic connections between the pin andlinestrips.

If desired, the tubes or pins, or both, may be slotted to form elasticconnections between. them, and thereby insure a more perfect contact.

The inagneto-engi 11c cinpl oyed in making the 'salls is attached to'abinding-post, L, on the back of the board, and this, bya wire, M,connects with an anvil, N, upon which rests the free end of a spring, 0,whose opposite end is joined to the call-andtelephone strip E by awireor other connection, P.

The spring 0 is operated by a push-pin, 0 on the face of the board, tobreak the connection with the magneto-engine and to throw the groundonto the telephone for thepurpose of talking.

The telephone is connected to binding-posts Q on the board, one postbeing joined by a wire, R, to a bridge, S, placed over that end ofspring 0 which bears upon the anvil, and the other post forming aground-eonncction for the telephone through the wire T, break spring U,and block \V', to which the groundwire is attached.

X X are disconnecting-drops placed on or off the board at any convenientpoint, one for each set of local connecting pin-strips B, and marked tocorrespond therewith. One wire, Y, from each of these drops is connecteddi rectly with one pin-strip of a set 13, and the other wire, Z,connected with the other pinstrip of the same set through the medium ofa fiat spring, A, and anvil B, upon which the free end of the springbears. One spring and one anvil are used with each disconnecting dropand each set B of pin-strips, and they are placed at any convenientpoint on or off the board.

O Gare flat springs arranged on the back of the board, under the springU,with the free ends beneath the free ends of the springs A, from whichthey are insulated by small rubber or other blocks, d,inserted in one orthe other spring, and they are also insulated from the spring U bysimilar blocks, 0, as shown in Figs. 3 and 4. The ends of the springs onthe board are connected by a wire, j", which also connects with one ofthe binding-posts ol' the telephone. These springs and their connectionsare employed in throwing off the ground from the telephone and inplacing the latter in the circuit of two lines. A wire, G, connects theother binding-post of the telephone with one of the bridges H over thesprings A of the disconnecting-drop attachment, the series of saidbridges being joined together by a continuation of the wire. Each bridgeH is further joined by a wire, I, to additional bridges, J, over thesprings U, as shown in Fig. 3.

Pusltpins K on the face of the board are arranged to be pressed againstthe springs for throwing the telephone into the circuit of any twolines, and for lifting the spring U olf the block to break theground-connecti on.

Instead of using a single long spring U for the whole number of lines, Iprefer to use a short spring for each line, as being the best and mostpracticable arrangement.

The operation of the switch -board thus far described is as follows: Thepins 0 nor mally occupy the'position shown in Fig. 1, to connect theannunciator-strips J with their respectiveline strips. Vhen, therefore,a call is made upon. any line, the magnet attracts an arn'lature of theannunciator and releases the drop connected with that line. To answersuch call, the operator at the switch-board shifts the pin 011 that linefrom the strip J to the call-and-telephone strip E, thereby breakstripof the set.

ing thecon'nection with the annunciator-drop and connecting theline-strip with the call-andtelephone strip. He then operates the engineto produce the necessary current for answering the call. Having thusannounced that the attention of the exchange is attracted, the op.-erator throws the telephone into the line by pressing in the push-pin Oto hold the spring 0 against the bridge S. This establishes a circuitfrom the ground through block W, spring U, wire T, the telephone, wireB, bridge S, and wire P to the call-and-telephone strip E, and fromthence to the line, as above described.

- If, now, the operator, beingin telephoniccommunication with the personwho has made the call, receives his instructions to connect said personsline with the line of another sub scriber, he releases the push-pin 0?,shifts the pin Cof the first line to one strip of any set of pinstripsfor the purpose of connecting it with the line-strip of said line. Hethen shifts the pin of the line called for from its annunciat'orstrip Jto the call-and-telephone strip, operates the engine to make the call,and pushes in the button 0 to connect said line with the telephone, sothat he can advise the subscriber of such line that heis wanted. by thesubscriber of the other line. Upon notification that the desiredsubscribers attention is secured, the operator removes the pin 0 of theline called from the call-and-telephone strip, and places it in theother pin-strip of the set containing the pin of the calling line, whichoperation connects the two lines through their discoifiiecting-drops. Todistinguish between the calling and called line, the pin of the callingline is placed in the lower strip of the set and the pin of the calledline in thehipper This enables the operator to tell at a glance whichline made the call.

7 It will be observed that all the line-strips cross the whole number ofpin-strips, and that i as the pin-strips are arranged in setsof two anytwolines can be connected by selecting the proper sets or groups. Forexample, re:

ferring to Fig. 3, if the left-hand line is to be connected with theright-hand line, the first pin is placed in the lower pin-strip of thesecond set from the bottom of the board to connect with the left-handline-strip. The other pin is placed in the upper pin-strip of the sameset to connect with the right-hand linestrip. Thetelephone-circuittaking this connection for'illustrationis from theleft-hand line and line-strip through the lower pin and pin-strip to theconnection with the wire Z, thence through said wire, the anvilB,'spring A, and the remainder of wire Z to the disconnecting-drop. Fromthe drop it passes through wire Y to the upper pin-strip of the set, andfrom thence to the third line-strip and its line. The circuit isrelatively'the same in all the sets and lines connected.

For the purpose of enabling the operator to tell when two lines areproperly connected and at work, he throws his telephone into the circuitof the two lines by pressing in the appro priate push button K. This, bybearing against the spring 0, lifts U from the block W to throw off theground and forces said spring 0 against the bridge J. The same movementlifts the spring A from the anvil B and bears said spring against itsbridge H; but there is no connection between the three springs by reasonof the insulators d e. The circuit is then from one part of wire Z- saythe short part, as shown in Fig. 3-to the other or long part of saidwire through the block B, wire 1, bridge J, spring 0, and wire f to thetelephone, thence through the telephone, the wire G, bridge H, andspring A to the long part of wire Z, the telephone being thus kept inthe circuit as long as the pressure is applied to the push-button. Bythis means the opera tor is enabled to determine whether or not the twolines are properly connected. When two persons have ceased talking overthe connected lines, one or the other, by calling back, causes thedisconnecting-drop of the two lines to fall, and thereby announce at theexchange that the lines are clear. By employing the line strips andpinstrips to make the connections between lines, cords for joining thepins are dispensed with, and the face of the board is kept clear andunobstructed, so that the operator is enabled to distinctly and rapidlytrace all the connections without confusion or mistake;

r Fig. 5 of the drawings shows a modification in the means forbi'eakingthe line-connections with two metal plates, L L, for each line-strip,

but disconnected therefrom. Their proximate edges are recessed, so thata pin, 0, inserted in an opening in the board between them shall touchtheir edges to effect theirconnection. The upper plate of each set isconnected by a wire, U, with the annunciator-drop {of its line, and thelower plate has a metallic connection on the back of the board with thefree end of a flat spring, M, which is spanned by a bridge, N. A secondspring, 0, is secured to the back of the board and rests at one end uponthe metal block by which the spring M is held in place, thereby making aconnection between the two springs. A bridge, P, spans the spring 0, andeach spring is provided with a push-pin on the face of the board, asshown by and there held while the telephone is used.

These are the temporary disconnections pre paratory to connecting twolines, and when the two lines to be joined have been indicated by theparties desiring to communicate with each other the pins C are removedfrom the plates L L of such lines and inserted in the pin-strips 1thereof. By this arrangement the repeated shifting of pins from theannunciator-strips to the call-and-telephone strips, and thence to thepin-strips, is avoided, only one change being necessary to cut off theannunciator and con nect two lines.

If the business of the exchange should at any time be so dull that allthe switch-boards are not required for constant use, then two or moremay be thrown together, to practically make one board under themanagement of one operator. This is eifectcd by the following means:

One end of each board is provided 011 its back with wires WV, joined tothe pin-strips, and the other end with two sets, X"X of short metalplates to receive set-screws or pins Z, inserted through the pin-stripsfrom the front of the board. The set X of these plates is used formaking and breaking the connections with the disconnecting-drops whenthe pins are applied, and the other set, X", is used for connectingcorreponding pin-strips of the'boards. To make the connections the wiresW on one board are joined to the plates X of the board next adjoining,and the pins or set-screws Z of the disconnecting-plates X on all theboards to be joined but one are loosened or removed to break theconnection with the pin-strips and cut out the disconnecting-drops,together with the apparatus for throwing the telephone into the circuitwith them. The set-screws or pins are then forced into theconnecting-plates Z to connect them with the line-strips B. This placesall the pin-strips under the control of one board, which preserves itsconnections with its own disconnecting-drops. All the other boards havetheir local connections with their lines for making and answering calls.

Any two or more boards, as well as the whole number, may be connected inthis manner, and one operator can manage them. If a call is made fromone board, he can connect the calling line with the called line of thesame or any other board in the connected group; but whichever lines arejoined the disconnectingdrops and telephone connected therewith areoperative from only one board of the group.

For the purpose of connecting the lines of one board with the lines ofother boards while each board preserves its independent operation, thereis placed on each board one or more combination pinstrips, D, connectingwith one or more of the sets of local pinstrips' B onthe other boards,the connections being made by wires. For example, supposing there arefive boards at the central oifice, (marked, respectively, A B C D E, asshown in- Fig. 6,)and each board provided with four-combinationpin-strips, D, and one set of local pin-strips B. Every board has itscombination pin strips lettered to correspond with the combineddesignating-letters of the other boards that is to say, board A has itsstrips lettered B O D E, and board B has its strips lettered A O D E,and so on for each board. The local pin-strips B on each board areconnected by wires with all the combination-strips of the other boards,which are lettered to correspond to the designating-letter of the boardbearing said local pin-strips. the set of local pin-strips on the Aboard is connected with the A strips on all the other boards, and theset of local pin-strips on the B board is connected with the B strips onall For example,

the otherboards. Additional combination pinstrips of the same letter maybe added to the boards; but each additional one must be con nected withanother of the sets B of local pinstrips added to the boards-that is tosay, another combination pin-strip marked A may be'added to all theboards; but this would require an additional set of local pin-strips tobe placed on board A, and another combina tion pi11strip, B, may beadded to all the boards, which would require an additional set of localpin-strips on the B board, and so on, making as many additions to theboards as may be required for the business of the oliice.

The independent operation of each board is preserved; but a line 011 oneboard may be connected to a line on another board by joining theline-strips on one, by means of pins 0, with its appropriate set oflocal pin strips, and then by like means joining the correspondingly-marked combination-strips with the linestrips of the board havingthe line to be connected.

I disclaim the combination of disconnecting drops with pinstrips,line-strips, and lines of the switch-board.

' Having thus described my invention, what I claim is 1. A telephoneswitch-board provided with a series of pin-strips grouped in pairs forcon;

necting two selected lines, and with a permanentline-strip for eachline, said pin and line strips being so arranged that any two linesshall be connected by inserting a metal pin in each pin-strip of thepair indicating such lines, so as to connect said strips with theline-strips of the lines to be joined.

2. The combination, with the independent linestrips and each set ofpin-strips, of a disconnectingdrop and line connected with saidpin-strips, and so arranged that any two telephone-lines can be joinedon the switch-board through said drops, substantially as described, forthe purpose specified.

3. The combination, on a telephone switchboard, of thecall-and-telephone strip E with the pin-strips B and linerstrips H,substantially as described, for the purpose specified.

4. The spring-switches A O and their connections with the line andtelephone, combined with the spring U, for taking off the ground of thetelephone and throwing the latter into the circuit of twolines, for thepurpose specified.

5. The combination of a series of telephone switch-boards and thedescribed connecting devices,whereby the combined boards are operated asone board, as herein set forth, for the purpose specified.

6. The combination, in a series of telephone switch-boards, of thelines, the pins, and the combination pin-strips, whereby the lines ofany one board of the series are joined to the lines of any other boardor boards, while the independent operation of 7 each board is preserved,substantially as described, for the purpose specified.

7. In a telephone switch-board, the combination of several series ofmetallic plates, each in connection with an independent line, withindependent bars across each series, each series of plates and barsforming one section, and switches to connect either line of one serieswith the bar or bars of its own section, and an. intermediate switch toconnect the bars of one section with the corresponding bars of anothersection.

8. In a telephone-exchange system, a series of connecting-strips, and aseries of branch circuits connected each with a pair of said strips, incombination with line-circuits and means for temporarily connecting anytwolinecircuits with a pair of connectingstrips.

9. In an electrical system having a number of line-circuits emanatingfrom a central ofiice,

a branch circuit, in combination with means for temporarily connectingit at opposite ends with any two of the line-circuits, as required,

and a switch for grounding said branch at an intermediate point.

10. The combination, with a series of circuits or conductors, of meansfor temporarily connecting any two of said circuits or conductors witheach other, as required, through a branch and switch mechanism forswitching one or more oentral-otfice instruments into and out of saidbranch. Y

11. The combination, with a central-office switch, of a series of mainlines for connecting any two of said lines for oral communication,apparatus included in each circuit to indicate a call or signal at thecentral office, and independent devices for connecting either line to apole-changing apparatus for transmitting outgoing signals. a

To the bove specification of my invention I have set my hand this th dayof Septemher, A. D. 1879.

EVERLYN B. HAMLIN.

-Witnesses:

CHARLES Boson, N. K. E LswoR'rH;

